1. Field of the Invention
The present invention relates to a technique of mounting a semiconductor chip on a semiconductor device, and more particularly to a technique of mounting a semiconductor chip on a TAB (Tape Automated Bonding) film.
2. Description of the Related Art
As integration density and functions of internal elements of a semiconductor chip have been increased, a semiconductor device package inevitably has a great number of pins. A TCP (Tape Carrier Package) is known as a package having a number of pins which is applicable to a LCD (Liquid Crystal Display) driver or an ASIC.
FIG. 4 shows a TAB film 20. The TAB film 20 includes a resin film 21, sprocket holes 22, a device hole 23 through which a semiconductor chip 30 is inserted, outer lead holes 24, a plurality of leads 25, and test pads 26 respectively connected to the leads 25.
FIGS. 5A and 5B show connection between the semiconductor chip 30 and the leads 25. As shown in FIG. 5A, an end portion (inner lead) 25a of the lead 25 is connected to a bump 32 formed on a pad 31 of the semiconductor chip 30. As shown in FIG. 5B, the leads 25 arranged in one line are respectively connected to the pads 31 arranged in one line.
In the above-described TAB film, a pad pitch l (shown in FIG. 5B) can be as small as 80 .mu.m according to the current practical technique. Since technique of forming more miniaturized inner elements of a semiconductor chip progresses more rapidly as compared to technique of mounting the semiconductor chip, the size of a semiconductor chip is determined by the number of pads. In other words, although internal elements of a semiconductor chip can be finer, a semiconductor chip cannot be so fine in accordance with the size of the elements. Therefore, the chip may include large dead space.
A semiconductor chip can be much smaller if two lines of pads are formed along one side of the chip. However, the conventional TAB mounting technique cannot mount a semiconductor chip having two lines of pads along one side thereof on a device.
As described above, the technique of mounting a semiconductor chip on a TAB film inhibits miniaturization of a chip.